Trying to teach a student with a domineering personality can be a challenge, so spare a thought for Count Emmanuel de las Cases, who was Napoleon Bonaparte's English teacher when both men were exiled on the island of St Helena following the battle of Waterloo in 1815.

Last month, one of just a handful of letters written by Napoleon in the language of his arch-enemies and sent to De las Cases for comment was sold at auction for $400,000, more than five times its anticipated price.

The one-page manuscript casts new light on Napoleon's melancholy exile, which ended with his death, aged 51, in 1821. But it will also strike a chord with any teacher tasked with correcting students' writing.

De las Cases recorded his time as imperial language teacher in his memoir and he says that Napoleon's writing practice, often composed, like this letter, during sleepless nights, was returned corrected without delay.

But where did De las Cases start? The 125 word text presents numerous language errors from grammar mistakes to lexis transferred from French.

It opens: "Count Las Case. It is two o'clock after midnight. I have enow [sic] sleep, I go then finish the night into cause with you..." "Cause" has been borrowed from the French word causer meaning to chat.

According to Jeremy Page, academic manager for English at Sussex University's centre for language studies: "Napoleon's opaque prose suggests he has learnt his English with scant regard for communicative priorities. There are instances of complex but imperfectly digested grammatical structures used with little attention to meaning or use."

Sadly De las Cases's reply does not survive so we do not know how he set about correcting his student's work, but if Napoleon's teacher were alive today he might be surprised to find correction and feedback of written work is a hot topic for debate.

Asking a student to write an email to a friend about what they did last weekend could be approached in two ways, he says. "If this is set as a productive activity for the past tense, then the micro-errors related to form should be dealt with. Alternatively if it is an email writing task then we need to consider it from a real-life point of view: does it match a reader's expectation of an email and does it convey a message? Teachers often fail to make these distinctions and the result is an overly corrected piece of work."

Agreeing a simple system for marking corrections on scripts should also be done in collaboration with students. And, after corrected work is returned, the student needs time to think about and question the marking, says Wilden.

"It's important that any 'correction' focuses on the bits students did well and the things they tried to do well. Red pen or not, it is demotivating to get a piece of work that is covered in the teacher's scrawlings," he said.

We don't know how De las Cases prepared his student for this letter-writing task, but Anna Schiffer, a senior teacher at the OISE English language school in Bristol, points out that assignments should start with pre-writing preparation.